Frame for semiconductor package

ABSTRACT

Frame F comprises plural lead frames  10  arranged through grid-leads L in matrix. Semiconductor devices are mounted on individual lead frames  10  of frame F, respectively and collectively molded with molding compound. Thereafter, the collectively molded semiconductor devices are cut at grid-leads L by means of dicing saw so that individual semiconductor packages are obtained. The frame F further has groove portions. The groove portions are formed by half-cutting by etching a metal of frame F from the front or back at areas corresponding to grid-leads, so that grid-frames are made thin. When a width of groove portions is larger than a width of dicing saw, cut burrs are reduced. When a width of groove portions is smaller than a width of dicing saw, the occurrence of metal powder dusts is restrained and time required for cutting becomes smaller.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a frame for semiconductorpackage in which a semiconductor device is mounted on a lead frame andthe outside thereof, particularly the upper surface of semiconductordevice is encapsulated with molding compound.

[0003] 2. Description of the Prior Art

[0004] In recent years, it has been required to miniaturize and shapesemiconductor product mounted on a substrate thinner, as packaging ofsemiconductor is made denser. It has been severely required for LSI toreduce the number of chips by improving integration level and tominiaturize and make a package lighter. The popularization of so-calledCSP (Chip Size Package) is rapidly advancing. Particularly, in thedevelopment of thin semiconductor product with lead frame, thesemiconductor package of single side encapsulation type has beendeveloped in which a semiconductor device is mounted on a lead frame andthe surface of semiconductor device mounted on a lead frame isencapsulated with molding compound.

[0005]FIG. 1 is a sectional view of one example of semiconductorpackage. FIG. 2 is a plan view thereof. The semiconductor package shownin FIGS. 1 and 2 is comprised of a lead frame 1, a semiconductor device4 mounted on die-pad 3 supported with suspending leads 2 of lead frame1, metallic thin wires 6 electrically connecting electrodes provided onthe top face of the semiconductor device 4 with terminals 5 of leadframe 1, respectively and molding compound 7 for encapsulating theoutside region of semiconductor device 4 including the upper side ofsemiconductor device 4 and the lower side of die-pad 3. Thesemiconductor package is of non-lead type in which so-called outer leadsare not projected from the semiconductor package and the two of innerleads and outer leads are integrated into terminals 5, wherein used leadflame 1 is half-cut by etching in such a manner that die-pad 3 ispositioned higher than terminals 5. Since such a step is formed betweendie pads 3 and terminals 5, molding compound 7 can be inserted into thelower side of die-pad 3 so that a thin semiconductor package can berealized even though the semiconductor package has non-exposed die-pad.

[0006] Since semiconductor device is miniature, a matrix type frame ismainly used for the above-mentioned semiconductor package of non-leadtype, in which plural semiconductor devices are arranged in a directionof a width of the matrix type frame. Further, recently, from a demandfor cost down, it is thought to switch over a frame of individuallymolding type shown in FIG. 3 to a frame of collectively molding typeshown in FIG. 4.

[0007] In the frame of individually molding type, as shown in FIG. 3(A),individual molding cavities C of small size are provided separatelywithin a frame F. After molding, individual semiconductor packages arestamped out so that semiconductor packages S shown in FIG. 3(B) areobtained. Namely, semiconductor devices are mounted on die-pads of leadframes through silver paste and others, and wire bonding is carried out.Thereafter, respective semiconductor devices are individually moldedwith molding compound and the respective molded semiconductor devicesare stamped out to form individual semiconductor packages.

[0008] In the frame of collectively molding type, as shown in FIG. 4(A),some molding cavities C of large size are provided within a frame F.Multiple semiconductor devices are arranged in matrix within eachmolding cavity C, respectively and collectively molded with moldingcompound. Thereafter, the collectively molded semiconductor devices arecut at grid-leads L by means of dicing saw so that a semiconductorpackage S shown in FIG. 4(B) is obtained. Namely, semiconductor devicesare mounted on die-pads of lead frames through silver pastes and othersand wire bonding is carried out. Thereafter, plural semiconductordevices arranged are collectively molded with molding compound to agiven cavity size, and then the collectively molded semiconductordevices are cut to form individual semiconductor packages by dicing.

[0009] The above-mentioned frame of collectively molding type has theadvantage that multiple resin-encapsulated packages can be produced allat once, therefore the productive efficiency being high. However, whencollectively molded semiconductor devices are cut to form individualpackages by means of dicing saw, molding compound and metallic leadframes are cut at the same time, in which cut burrs of metal of leadframe are projected largely to adjacent terminals of lead frame by whichshort circuit is formed. Further, there is a problem that metal powdersdusts generated pollute the environment and dicing saw is apt to wearout since metal is shaved with the dicing saw.

BRIEF SUMMARY OF THE INVENTION

[0010] An object of the present invention is to provide a frame forsemiconductor package of collectively molding type used for theproduction of semiconductor package, in which cut burrs of metalgenerated when cutting molded resin and metal of lead frame by means ofdicing saw are reduced or the generation of dusts of metal is inhibited,and the wear of dicing saw is reduced.

[0011] In order to achieve the above-mentioned object, a frame forsemiconductor package of the present invention comprises plural leadframes arranged in matrix through grid-leads, in which individualsemiconductor devices are mounted on the individual lead frames,respectively, the semiconductor devices are collectively molded withmolding compound and the collectively molded semiconductor devices arecut at grid-leads by means of dicing saw to obtain individualsemiconductor packages, wherein the grid-leads are provided with grooveportions which are formed by half-cutting by etching areas of the framefor semiconductor package corresponding to the grid-leads from the frontor back thereof in such a manner that thin grid-leads are formed.

[0012] In the above-mentioned lead frame, a width of groove portions maybe larger or smaller than the width of dicing saw.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a sectional view of one example of semiconductorpackage.

[0014]FIG. 2 is a plan view of semiconductor package shown in FIG. 1.

[0015]FIG. 3 is an explanatory view of a frame of individually moldingtype.

[0016]FIG. 4 is an explanatory view of a frame of collectively moldingtype.

[0017]FIG. 5 is a plan view of one example of a frame of the presentinvention seen from the front side thereof.

[0018]FIG. 6 is a partial enlarged plan view of a frame shown in FIG. 5.

[0019]FIG. 7 is a sectional view taken on line A-A of FIG. 6.

[0020]FIG. 8 is a sectional view showing a modification of example ofFIG. 6.

[0021]FIG. 9 is a sectional view of another example of frame showncorresponding to FIG. 7.

[0022]FIG. 10 is a sectional view showing a modification of example ofFIG. 9.

DETAILED DESCRIPTION

[0023] Then, referring to figures, embodiments of the present inventionsare explained. FIG. 5 is a plan view of one example of a frame of thepresent invention. FIG. 6 is a partial enlarged plan view of the frame.FIG. 7 is a sectional view taken on line A-A of FIG. 6.

[0024] In FIG. 5, F designates a metal frame for lead frame, in whichlead frames 10 are arranged in a matrix of 3×4 through grid-leads L. Thegrid-leads L connect terminals 11 of adjacent lead frames 10 with eachother. Then, as shown in FIGS. 6 and 7, the metal frame has lineargroove portions 12 which pass through areas of backside of lead framecorresponding to grid-leads L. The groove portions 12 are formed byhalf-cut by etching the metal frame. Further, groove portions 12 withthe same width are provided around the whole of twelve lead frames.

[0025] Process for producing semiconductor packages using the frame F isas follows. First, semiconductor devices are mounted on die-pads 13 ofthe respective lead frames 10 of frame F through silver pastes and wirebonding is made between terminals 11 of lead frame and electrodesprovided on the top face of semiconductor devices. Thereafter, twelvesemiconductor devices are collectively molded with molding compound to agiven cavity size and then the collectively molded semiconductor devicesare cut at grid-leads L by means of dicing saw in such a manner thatterminals 11 of individual lead frames are left, by which thecollectively molded semiconductor devices are divided into individualsemiconductor packages.

[0026] In this case, when a width of groove portions 12 is the same as awidth of dicing saw, there is a case where edge of dicing saw fits intogroove potion 12 so that cutting does not go smoothly. Further,according to accuracy of setting of dicing saw to groove portions 12,shapes of section of metal varies with individual sides so thatvariation in connecting strength of substrate is generated in mountingof semiconductor device. Therefore, a width of groove portions 12 is setto be larger or smaller than a width of dicing saw in such a manner thatcutting can be carried out smoothly.

[0027] When cutting the collectively molded semiconductor devices, metaland resin are cut at grid-leads L from the front side of collectivelymolded semiconductor devices, in which when a width groove portions 12is larger than width a of dicing saw as shown in FIG. 7, since metal isremoved at groove portions 12, the generation of metal burrs becomessmaller. Further, even if grove portions 12 having a width larger thanwidth “a” of dicing saw is provided on the front side of frame forsemiconductor package, burrs also become hard to occur. However, sincethe collectively molded semiconductor devices are cut from the frontside of frame for semiconductor package, it is preferable that grooveportions 12 are provided on the backside of frame.

[0028] Further, when a width of groove portions 12 is smaller than widtha of dicing saw as shown in FIG. 9, metal is cut to generate burrs.However, since amount of metal to be cut is small, the generation ofmetal powder dusts is inhibited and even if time required for cutting issmall, cutting is made sufficiently.

[0029] As above-mentioned, a frame for semiconductor package of thepresent invention comprises plural lead frames arranged in matrixthrough grid-leads. Individual semiconductor devices are mounted on theindividual lead frames, respectively, the semiconductor devices arecollectively molded with molding compound and the collectively moldedsemiconductor devices are cut at grid-leads by means of dicing saw toobtain individual semiconductor packages, wherein the grid-leads areprovided with groove portions which are formed by half-cutting byetching areas of frame for semiconductor package corresponding to thegroove portions from the front or back thereof in such a manner thatthin grid-leads are formed. When a width of groove portions is largerthan a width of dicing saw, area of cross section to be cut by dicing isdecreased so that cut burrs are lessened in such an extent that burrsare not projected largely. Therefore, accident of short circuit becomesnothing. Further, when a width of groove portions is smaller than awidth of dicing saw, amount of metal to be cutting is decreased so thatthe generation of metal powder dusts is inhibited, time required forcutting becomes smaller and damage of dicing saw is lessened.

What is claimed is:
 1. A frame for semiconductor package comprising plural lead frames arranged in matrix through grid-leads, in which individual semiconductor devices are mounted on the individual lead frames, respectively, the semiconductor devices are collectively molded with molding compound and the collectively molded semiconductor devices are cut at grid-leads by means of dicing saw to obtain individual semiconductor packages, wherein the grid-leads are provided with groove portions in such a manner that thin grid-leads are formed.
 2. A frame for semiconductor package as claimed in claim 1 , wherein groove portions are formed by half-cutting by etching areas of the frame for semiconductor package corresponding to the grid-leads from the front or back thereof.
 3. A frame for semiconductor package as claimed in claim 1 , wherein a width of groove portions is larger than a width of dicing saw.
 4. A frame for semiconductor package as claimed in claim 1 , wherein a width of groove portions is smaller than a width of dicing saw. 